title: Osteoblasts promote engraftment of allogeneic hematopoietic stem cells.
abstract: Hematopoietic progenitor cells (low density, lineage negative [Lin-], depleted of CD4+, CD8+, B220+, Gr-1+, Mac-1+, CD71+, and Thy1.2+ cells) can engraft lethally irradiated mice when transplanted within, but not across the major histocompatibility (MHC) antigen barrier. We hypothesized that our progenitor cell preparation required "supportive" cells/factors for successful engraftment. Our initial candidate supportive cells, dendritic cells, failed to facilitate engraftment of stem cells across fully allogeneic MHC barriers. Because interaction of stem cells with bone marrow (BM) stromal microenvironment is required for development, maturation, and differentiation of hematopoietic stem cells, and because bone transplants have been found to facilitate BM transplantation (BMT) in some strain combinations, we tested bone progenitor cells, osteoblasts, as facilitators of allogeneic stem cell engraftment. Osteoblasts, purified from donor murine long bones, were cotransplanted with marrow stem cells into fully allogeneic mouse strains. The transplanted mice demonstrated excellent long-term survival, were free of disease, and were entirely engrafted with cells of donor origin. Histologic sections of thymuses and spleens showed full reconstitution of lymphohematopoietic elements. Surprisingly, in contrast to fully allogeneic chimeras reconstituted by allogeneic T lymphocyte-depleted BM, our stem cell chimeras were found to produce an impressive primary antibody response to the cellular antigen, sheep red blood cells. Thus, bone progenitor cells or osteoblasts may represent an essential component of the stromal cell population and facilitate engraftment of marrow stem cells in an allogeneic environment.
authors.affiliation: Department of Pediatrics, All Children's Hospital/University of South Florida, St. Petersburg 33701, USA.
authors.forename: N S
authors.initials: NS
authors.lastname: El-Badri
authors.forename: B Y
authors.initials: BY
authors.lastname: Wang
authors.lastname: Cherry
authors.forename: R A
authors.initials: RA
authors.lastname: Good
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002113:Calcification, Physiologic; D002469:Cell Separation / Q000379:methods; D003713:Dendritic Cells / Q000166:cytology*; D005109:Extracellular Matrix / Q000502:physiology; D005260:Female; D018380:Hematopoietic Stem Cell Transplantation; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000502:physiology*; D006650:Histocompatibility Testing; D016130:Immunophenotyping; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D010006:Osteoblasts / Q000166:cytology / Q000502:physiology* / Q000637:transplantation*; D017154:Stromal Cells / Q000166:cytology; D018183:Transplantation Chimera / Q000276:immunology; D014184:Transplantation, Homologous / Q000502:physiology*
chemical_list: D000469:Alkaline Phosphatase